Abstract : Rechargeable lithium batteries are widely recognized as excellent candidates as power sources for applications where energy and power density are critical. One promising lithium battery technology is based on polymer electrolytes. The often cited advantages of polymer electrolyte batteries include: stability toward electrodes that provide high energy density, greater safety than liquid electrolyte batteries, ruggedness, low self-discharge rates, ability to accommodate temperature excursions, and moderate cost. Despite these predictions, polymer electrolyte batteries are not yet commercially available. The lack of fully commercial lithium-polymer batteries (other than highly specialized batteries such as those in heart pacemakers) is associated with several factors. One problem is the comparatively low electrolyte conductivity, which can only be partly compensated by use of thin electrolyte films. Another problem is the poor low-temperature conductivity of most polymer electrolytes. A third issue with polymer electrolytes is the relatively low transference number for cations. Our research group has addressed these issues in the development of phosphazene, siloxy and aluminosilicate polyelectrolytes with improved low temperature performance and unity transference number for cations. The complex dielectric and electrochemical properties of these materials have been extensively investigated in our laboratory.